11 Answers

6 votes

With strong moves like Close Combat, Stone Edge, and Stealth Rock dominating the competitive metagame, Cloyster doesn't seem as bulky as it used to. So I think THIS will the be the new generation's standard:

Ability: Skill Link
Nature: Naive/Jolly
EVs: Speed, lots of it!
*Shell Break - acts like Swords Dance, Nasty Plot, and Agility all in one technique! But it comes at the cost of -2 Defense AND Sp. Defense. Cloyster has godly Defense AND poor Sp. Defense and, as stated, Cloyster can't really take advantage of its natural bulk anyway thanks to Stealth Rock, Close Combat, and Stone Edge and no reliable means of recovery so it doesn't really matter either way.
*Icicle Spear - STAB, and gains an insane 187 base power (STAB included) thanks to Skill Link!
*Rock Blast - coverage, gains 125 base power also because of Skill Link.
*Surf/Razor Shell - choose your other STAB attack based on the nature. I recommend a mixed set to deal with walls and so Shell Break's Sp. Attack boost isn't wasted.

Okay then, Focus Sash allows you to get up Shell Smash. Now you have Skill Link, which makes your STAB Icicle Spear and Rock Blast do a ton of damage while also breaking through Substitute, Sturdy, and Focus Sash. Razor Shell provides STAB, and also has a good chance of lowering the defense of the foe, which could be helpful for foes with defense boosts or resistances. Standard sweeping EVs.

I have one like that and a slightly different one that works pretty well,
Instead train both defenese fully and use a white herb
White herb to counter the stat drops from shell smash and still get the speed and attack boosts!

Special Cloyster

This clam is famous in OU for its bulk and Shell Smash sweeping capabilities, and although Cloyster is kind of a nub Pokemon, that is no reason for me to not realize it is always used as a Physical Attacker, and try to make use of its less significant SAtk. It is not able to surprise the enemy by Shell Smashing, but it IS able to pull some shenanigans by being a special attacker, which can allow it to get around many of the things that give physical variants trouble, such as Skarmory, Ferrothorn, and mostly Steel types that can be found running Physically Defensive sets as a standard. Hydro Pump is STAB, Ice Beam is secondary STAB and they are pretty much Cloyster's special versions of Razor Shell and Icicle Spear. The last attacking option is usually a split between HP Grass or Electric for hitting bulky water types, Grass for things like Gadtrodon and Rorom-W, and Electric for Pokemon such as Gyarados and Skarmory better. However, should you decide that you already have buly waters coveted, Hidden Power Fire is an option for bringing down Ferrothorn, Skarmory, Magnezone, and the occasional Abomasnow. Another perk of Special Cloyster is that it can run Overcoat, meaning it can not be worn down by Sand, which would render any physical variant's Focus Sashes useless.

This set is done better by several other pokemon, but Cloyster can still fit a nice Niche on weather teams and anti weather teams. The spikes damage the opponent, while ice shard is there to break through various pokemon. He's a support cloyster in this sense rather than rampaging with shell smash. Sand teams rely a lot on building up damage and finishing things off with high powered attackers. The spikes will poison plenty of pokemon and wear at them. He would go great with a partner with ground moves, so as to deal with the pokemon this will draw out, like Nidoking, Heatran, Reunilicus, etc. A spin blocker would also be in order. Golurk makes a nice partner since Cloyster can switch in without fear of fighting or rock moves. He has to watch out for grass moves, but those are a lot easier to predict than the other more common moves.

You can go physical with a Careful nature, and the first EV spread, Making use of Skill Link. Rock Blast is still beastly back in Gen IV, so you can work with that. Poison Jab is a great way to have a main attacking move ( You need those ingame ) That you can drain your PP on, Spike Cannon gives you great neutral hits on Those annoying Trainer battles, and Avalanch, Icicle Spear, or Ice Shard gives you whatever Ice coverage you want for him.
Special set uses either ability, although the second one is prefered, Calm Nature, and the second Ev spread. Mud Shot and HP [Anything] are your options for your first slot, not too bad. Surf is hard hitting STAB and that much needed transportation, although in HG / SS you might want Whirlpool if you already have a surf user, and Brine can be used for great strategies, but isn't the best choice might I add. Signal Beam is gotten from a move tutor, but if you can get it, it works well. While Whirlpool is there again if you want a surfer and a Whirlpooler. Last slot is Ice Beam, which is a stand alone boss move for ingame and competitive.

I'd say risk it. I don't usually support stat boosting in Double/Triple battles because it is so incredibly risky and is usually not going to be worth the risk. However, Shell Smash Cloyster might be worth the risk. Surf and Blizzard are STAB that hit multiple foes. HP Electric is coverage.